1. Field of the Invention
The present invention relates generally to packet switched networks, and more specifically to low-cost implementation of a high-capacity packet switched network. The present invention is particularly concerned with a packet switched network using different protocols such as X.25 protocol and IP protocol.
2. Description of the Related Art
As shown in FIG. 1, a data communication network such as the packet switched network specified by ITU-T (International Telecommunication Union-Telecommunication Standardization Sector) Recommendation X.25, is generally organized in groups of X.25 packet switches 120, packet multiplexers 130 and X.25 subscriber packet terminals 100. Packet switches 120 are interconnected by communication links to form a packet network. Host computers 110 are connected to the packet switches 120 to communicate with the subscriber packet terminals 100. Packet multiplexers 130 concentrate the uplink traffic from the packet terminals 100 to the packet network and deconcentrate the downlink traffic from the packet network to the packet terminals. However, because of its independent and dedicated nature, a huge investment cost is required to build a high-capacity X.25 packet switched network. Additionally, the communication links of the X.25 packet network are usually implemented with leased lines or ISDN facilities supplied from network providers. As a result, the subscribers have to bear high communications costs.